Release of Prostaglandins During Contraction of the Human Umbilical Vein on Reduction of Temperature

Boura, A. L. A.; Boyle, Lyndall; Sinnathuray, T. A.; Walters, W.A.W.

doi:10.1111/j.1476-5381.1979.tb07838.x

Cited by 20 publications

(12 citation statements)

References 9 publications

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“…It is also possible that the low temperature of cold, dry gas during PACI may have reduced clearance of CO 2 from the fetal compartment. Reducing the temperature of umbilical vessels from body temperature to 22 • C may cause vessel vasoconstriction and reduce umbilical blood flow 20 . Indeed, we observed reductions in umbilical venous flow in fetuses undergoing PACI with cold, dry gas, and the associated reduction in placental perfusion likely reduced CO 2 clearance, adding to the fetal hypercapnia.…”

Section: Discussionmentioning

confidence: 99%

Physiological effects of partial amniotic carbon dioxide insufflation with cold, dry vs heated, humidified gas in a sheep model

Amberg

Hodges

Kashyap

et al. 2019

Ultrasound in Obstet & Gyne

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Objective Partial amniotic carbon dioxide (CO 2 ) insufflation (PACI) is used to improve visualization and facilitate complex fetoscopic surgery. However, there are concerns about fetal hypercapnic acidosis and postoperative fetal membrane inflammation. We assessed whether using heated and humidified, rather than cold and dry, CO 2 might reduce the impact of PACI on the fetus and fetal membranes in sheep. Methods Twelve fetal lambs of 105 days' gestational age (term = 145 days) were exteriorized partially, via a midline laparotomy and hysterotomy, and arterial catheters and flow probes were inserted surgically. The 10 surviving fetuses were returned to the uterus, which was then closed and insufflated with cold, dry (22 °C at 0–5% humidity, n = 5) or heated, humidified (40 °C at 100% humidity, n = 5) CO 2 at 15 mmHg for 180 min. Fetal membranes were collected immediately after insufflation for histological analysis. Physiological data and membrane leukocyte counts, suggestive of membrane inflammation, were compared between the two groups. Results After 180 min of insufflation, fetal survival was 0% in the group which underwent PACI with cold, dry CO 2 , and 60% ( n = 3) in the group which received heated, humidified gas. While all insufflated fetuses became progressively hypercapnic (PaCO 2 > 68 mmHg), this was considerably less pronounced in those in which heated, humidified gas was used: after 120 min of insufflation, compared with those receiving cold, dry gas ( n = 3), fetuses undergoing heated, humidified PACI ( n = 5) had lower arterial partial pressure of CO 2 (mean ± standard error of the mean, 82.7 ± 9.1 mmHg for heated, humidified CO 2 vs 170.5 ± 28.5 for cold, dry CO 2 during PACI, P < 0.01), lower lactate levels (1.4 ± 0.4 vs 8.5 ± 0.9 mmol/L, P < 0.01) and higher pH (pH, 7.10 ± 0.04 vs 6.75 ± 0.04, P < 0.01). There was also a non‐significant trend for fetal carotid artery pressure to be higher following PACI with heated, humidified compared with cold, dry CO 2 (30.5 ± 1.3 vs 8.7 ± 5.5 mmHg, P = 0.22). Additionally, the median (interquartile range) number of leukocytes in the chorion was significantly lower in the group undergoing PACI with heated, humidified CO 2 compared with the group receiving cold, dry CO 2 (0.7 × 10 –5 (0.5 × 10 –5 ...

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Section: Discussionmentioning

confidence: 99%

Physiological effects of partial amniotic carbon dioxide insufflation with cold, dry vs heated, humidified gas in a sheep model

Amberg

Hodges

Kashyap

et al. 2019

Ultrasound in Obstet & Gyne

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show abstract

“…The vessels were dissected out while the cord was still immersed in de-oxygenated Krebs saline maintained at a low 02 tension by bubbling with 95 % N2/5 % CO2. This keeps the gas tensions at fetal levels but allows cooling, which on its own may still lead to contraction through release of prostaglandins (Boura, Boyle & Sinnathuray, 1979). Nevertheless, this method has proved satisfactory in providing viable preparations.…”

Section: Methodsmentioning

confidence: 99%

“…Cords from full-term pregnancies were obtained from the Queen (Boura, Boyle & Sinnathuray, 1979). Nevertheless, this method has proved satisfactory in providing viable preparations.…”

Section: Methodsmentioning

confidence: 99%

Contraction of human umbilical artery, but not vein, by oxygen.

McGrath¹,

MacLennan²,

Mann³

et al. 1986

The Journal of Physiology

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SUMMARY1. The 02 tension of umbilical arterial blood in utero is 15 mmHg. The contractile effect of increasing the 02 tension above this value was studied quantitatively in vitro in preparations of human umbilical artery and vein.2. The umbilical arterial smooth muscle was contracted in a concentration-related manner by stepped increments in 02 tension. The threshold for O2-induced contraction was estimated to be 36 mmHg at pH 7-28 and the maximum contraction occurred at 297 mmHg.3. The sensitivity of the preparations to low 02 tensions (<100 mmHg) was reduced by increasing the pH of the bathing medium from 7-28 to 7-36, at which the threshold was 69 mmHg and the maximum contraction occurred at 282 mmHg.Reducing the pH to 7418 did not significantly change the sensitivity from that found at pH 7-28.4. Indomethacin (0-1 ,tM) virtually abolished responses to 025. The results indicate that the increase in the physiological 02 tension at birth, from 15 to 100 mmHg, may be an adequate stimulus to effect the closure of the umbilical artery.6. In the physiological range 02 did not contract the umbilical venous smooth muscle. This may allow the transfusion of blood from the placenta to the fetus at birth when the 02 tension of umbilical cord blood increases after the onset of breathing.

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“…The technique used for collection of the cords and perfusion of the vein has been described in detail by Boura et al (1979) and Sandford et al (1981). One to two minutes after delivery of the baby, and before delivery of the placenta, two umbilical clamps were applied to the cord near its emergence from the vagina and a further two placed 15 cm from the umbilicus.…”

Section: Umbilical Vein Perfusionmentioning

confidence: 99%

Effects of vasoactive autacoids on the human umbilical‐fetal placental vasculature

Mak

Gude

Walters

et al. 1984

BJOG

125

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summary Studies have been made of the effects of autacoids on vascular tone of the human perfused fetal umbilical vein and placental lobule. The thromboxane A2 (TxA2)‐mimetic substance U46619, 5‐hydroxytryptamine and bradykinin were powerful constrictors of the vein. Prostaglandins E2 (PGE2), F2α(PGF2α), adrenaline, noradrenaline, histamine and angiotensin II were much less potent. Venoconstriction caused by U46619, bradykinin and 5‐hydroxytryptamine was reduced during inhibition of phospholipase A2 with mepacrine. Responses to U46619 were also reduced after inhibition of cyclo‐oxygenase with indomethacin whereas those to bradykinin and 5‐hydroxytryptamine were potentiated. In the placenta U46619 was the most potent vasoconstrictor, bradykinin, 5‐hydroxytryptamine, angiotensin II, PGE2 and PGF2α being 10–100 times less active. Responses to U46619 were reduced by either mepacrine or indomethacin. Arachidonic acid caused umbilical venoconstriction but vasodilatation in the placenta. Both effects were reduced by indomethacin. Prostacyclin (PGI2) caused vasodilatation in both preparations. It is suggested that TxA2 in the placenta and TxA2, 5‐hydroxytryptamine and bradykinin in the umbilical vein could contribute to control of vascular smooth muscle tone. Their vasoconstrictor effects are partly indirect and affected by the concomitant local release of eicosanoids. The results add suort to previous conclusions that these autacoids may normally have important influences on blood flow in the fetal extra‐corporeal circulation. Agents inhibiting their synthesis, eg non‐steroidal anti‐inflammatory agents, should only be prescribed during pregnancy with these facts in mind.

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Release of Prostaglandins During Contraction of the Human Umbilical Vein on Reduction of Temperature

Cited by 20 publications

References 9 publications

Physiological effects of partial amniotic carbon dioxide insufflation with cold, dry vs heated, humidified gas in a sheep model

Physiological effects of partial amniotic carbon dioxide insufflation with cold, dry vs heated, humidified gas in a sheep model

Contraction of human umbilical artery, but not vein, by oxygen.

Effects of vasoactive autacoids on the human umbilical‐fetal placental vasculature

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